To date chlorofluorocarbons (CFCs) have been used as refrigerants and propellants. However, it is a chlorofluorocarbon that has been identified as depleting atmospheric ozone. The Montreal Accords restrict the production of chlorofluorocarbons. Potential CFC replacements for these refrigerants include hydrofluorocarbons (HFCs), such as the tetrafluoroethanes, and hydrochlorofluorocarbons (HCFCs), such as difluorochloromethane.
Hydrofluorocarbons are of particular interest as substitute refrigerants because of low toxicity, low ozone depletion potential, low global warming potential, and non-flamability. However, making this substitution is problematic since mineral oil, the lubricant previously used for the CFCs, is not compatible with HFC. Incompatible lubricants will not be properly transported throughout a refrigeration system during operation resulting in improper compressor lubrication and accumulation of lubricant in parts of the refrigeration system. Improper lubrication reduces the efficiency of a refrigeration system, as well as shortening the lifetime of the system.
As discussed in Alpha Olefin Applications Handbook; Marcel Dekker, Inc., 1989; Chapter 13, poly .alpha.-olefins are well known lubricants. For example, "Mobil 1" (in part poly-1-decene oligomer) and "Shell W" aviation oil holy .alpha.-olefin/mineral oil blend) are considered to be particularly useful lubricants for engines, in particular piston engines. Unfortunately, poly .alpha.-olefins, like mineral oils, are immisicble in tetrafluoroethane refrigerants.
U.S. Pat. No. 4,832,859 describes lubricants containing at least one compound of the formula: ##STR1## R.sub.f is a perfluorinated radical; a=0 to 10; b=0 to 1 (if a=0 and c=1); c=1 to 4 (2 if a.noteq.0); m=0 or 1; n=0 or 1; X is an aryl radical; Y is a 2-hydroxy-1-phenylethyl group; R.sub.1 and R'.sub.1 each represent a hydrogen atom or an alkyl, cycloalkyl or aryl radical; R.sub.2 and R'.sub.2 each represent a hydrogen atom or an acyl residue, at least one of the symbols R.sub.1 +R.sub.2 being other than F or CH.sub.3 if the sum of a+m+n=0.
U.S. Pat. No. 4,944,890 describes a blend of refrigerant with at least one fluorinated hydrocarbon, in which the weight ratio of fluorine-to-carbon is from about 0.5 to 5, and which has an SUS viscosity at 100.degree. F. of at least 50, wherein the refrigerant is HFC-134a and the fluorinated hydrocarbon polymer has the formula (R.sub.f (CH.sub.2).sub.n CH=CH.sub.2).sub.m, where the number of carbon atoms in the R.sub.f group is 2 to 20 and n=0 or 1.
U.S. Pat. No. 5,032,306 describes a blend of refrigerant with at least one fluorinated hydrocarbon comprising at least one graft of a perfluoroalkene or a perfluoroalkyvinyl ether onto at least one hydrocarbon having at least four (4) carbon atoms.
U.S. Pat. No. 4, 975,212 describes a lubricating composition comprising a polyoxyalkylene glycol having a cap of a fluorinated alkyl group on at least one terminal end thereof and miscible with tetrafluoroethane or blends of tetrafluoroethane with other refrigerants miscible with the lubricant in the range of about -40.degree. C. to at least 20.degree. C. are included.
U.S. Pat. No. 4,931,199 describes the use of chlorofluoropolyethers, such as perfluoropolyepichlorohydrins as lubricants for cooling systems that employ hydrofluorocarbon refrigerents, such as 1,1,1,2-tetrafluoroethane.
EPO 353 935 describes a lubricant additive comprising at least one terminally unsaturated ethylene .alpha.-olefin polymer substituted with mono- or dicarboxylic acid.
A useful review on reactions of the HFIFP oligomers is given in J. Fluorine Chem. 1977, 10(4), 323-7.
Furthermore, synthetic methods for derivatizing TFE oligomers has been described in U.S. Pat. No. 4,154,753 and such description is incorporated herein by reference. In that patent, R.sub.f (OR).sub.x compounds are described wherein the R groups contains a hydrophilic moiety.